Ginseng root is one of the most widely recognized herbal supplements with increased clinical evidence of potential benefits in cardiovascular diseases. Studies have shown that ginsenosides, active constituents of ginseng, have protective roles in atherosclerotic plaque formation and various vascular injuries. We hypothesize that ginseng root and ginsenoside have protective effects against angioplasty-induced vascular damage and post-angioplasty restenosis. We recently have demonstrated that ginsenoside Rb1 (Rb1) blocks homocysteine (HCY)-induced detrimental effects on endothelial vasomotor function, free-radical production, and eNOS expression. To extend the preliminary studies, we propose a more comprehensive investigation to elucidate the molecular mechanisms, cellular effects, and in vivo influences of Rb1 on HCY- exaggerated cellular stress following vascular injury. Our central hypothesis is that Rb1 effectively blocks HCY-augmented vascular dysfunction and restenosis by maintaining a functional eNOS system and decreasing oxidative stress. Two specific aims are proposed: Specific Aim 1: Determine the molecular mechanisms of Rb1-medicated eNOS rescue and ROS suppression in HCY-induced cellular stress. Hypothesis: both eNOS dysfunction and oxidative stress play important roles in HCY-induced atherogenesis and restenosis. These two systems are intimately related, yet distinct entities. Rb1 exerts its protective effects by modulating eNOS expression and O2.- production. In this aim, we will study the eNOS system by analyzing eNOS expression, activity, and regulation in human coronary artery endothelial cells (HCAECs) (Specific Aim 1a). We will also investigate the sources of reactive oxygen species (ROS) production in HCAECs and determine whether ROS-mediated signaling pathway is involved in HCY-induced endothelial dysfunction (Specific Aims 1b). Specific Aim 2: Determine the effects of Rb1 on HCY-augmented intimal hyperplasia in a post-guide wire injured murine model. A guidewire-induced common carotid artery injury model in Apolipoprotein E deficient (ApoE-/-) mice will be used. Degree and composition of restenosis will be monitored using a molecular imaging techniques and histology methods. This application may potentially lead to a new strategy of incorporating complementary and alternative medicine to ameliorate HCY-associated cellular stress and post-angioplasty intimal hyperplasia. Development of ginseng compounds is a great opportunity given their history of therapeutic applications and recent discoveries of their molecular actions. Our application utilizes a multidisciplinary approach to explore the mechanisms and in vivo effects of Rb1. We hope that this application will establish a solid foundation for large- scale clinical research and potentially provide an alternative treatment strategy for vascular damages and restenosis. PUBLIC HEALTH RELEVANCE: This application utilizes a comprehensive molecular, cellular, and animal model approach to investigate the effects and mechanisms of ginsenoside Rb1 on homocysteine-exaggerated vascular dysfunction. This application may potentially lead to a new strategy of incorporating complementary and alternative medicine to ameliorate risk factor-associated cellular stress. We hope that our investigation will establish a solid foundation for large-scale clinical research and provide an alternative treatment strategy for vascular restenosis in an aging population.